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From:   Ian Rogers <irogers@google.com>
Date:   Tue, 12 Dec 2023 10:08:18 -0800
Message-ID: <CAP-5=fW+iS8J=DVW3qmQK9n0y1vLkZxn62JX8D8ETTWBtuq09A@mail.gmail.com>
Subject: Re: [PATCH 3/3] perf unwind-libunwind: Fix base address for .eh_frame
To:     Namhyung Kim <namhyung@kernel.org>
Cc:     Arnaldo Carvalho de Melo <acme@kernel.org>,
        Jiri Olsa <jolsa@kernel.org>,
        Adrian Hunter <adrian.hunter@intel.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        linux-perf-users@vger.kernel.org,
        Milian Wolff <milian.wolff@kdab.com>,
        Pablo Galindo <pablogsal@gmail.com>,
        Fangrui Song <maskray@google.com>
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On Mon, Dec 11, 2023 at 11:05=E2=80=AFPM Namhyung Kim <namhyung@kernel.org>=
 wrote:
>
> The base address of a DSO mapping should start at the start of the file.
> Usually DSOs are mapped from the pgoff 0 so it doesn't matter when it
> uses the start of the map address.  But generated DSOs for JIT codes
> doesn't start from the 0 so it should subtract the offset to calculate
> the .eh_frame table offsets correctly.
>
> Fixes: dc2cf4ca866f ("perf unwind: Fix segbase for ld.lld linked objects"=
)
> Signed-off-by: Namhyung Kim <namhyung@kernel.org>

Reviewed-by: Ian Rogers <irogers@google.com>

Thanks,
Ian

> ---
>  tools/perf/util/unwind-libunwind-local.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tools/perf/util/unwind-libunwind-local.c b/tools/perf/util/u=
nwind-libunwind-local.c
> index c0641882fd2f..5e5c3395a499 100644
> --- a/tools/perf/util/unwind-libunwind-local.c
> +++ b/tools/perf/util/unwind-libunwind-local.c
> @@ -327,7 +327,7 @@ static int read_unwind_spec_eh_frame(struct dso *dso,=
 struct unwind_info *ui,
>
>         maps__for_each_entry(thread__maps(ui->thread), map_node) {
>                 struct map *map =3D map_node->map;
> -               u64 start =3D map__start(map);
> +               u64 start =3D map__start(map) - map__pgoff(map);
>
>                 if (map__dso(map) =3D=3D dso && start < base_addr)
>                         base_addr =3D start;
> --
> 2.43.0.472.g3155946c3a-goog
>